Light from a laser is monochromatic, coherent, highly directional, and can be focused into a very small region.
Laser light, like that of an ordinary light bulb, is emitted when the atoms of an element undergo a transition to a lower-energy quantum state. However, in the laser, unlike with other light sources, the atoms work together to produce light with several special characteristics.
1st characteristic: The light of a laser is monochromatic.Light from an ordinary incandescent lamp has a wide range of wavelengths. The light emitted by a fluorescent lamp is concentrated in a few wavelengths, but the spectral lines are relatively wide. A laser produces narrower spectral lines than other light sources.
2nd characteristic: The light of a laser is coherent. Even if two light beams produced by the same laser are separated and recombined after traveling hundreds of kilometers, there will still be a definite relationship between the phases of the two beams and they will be able to form an interference figure. This property is called coherence. In the case of an ordinary lamp, the coherence distance is less than one meter.
3rd characteristic: The light of a laser is highly directional: the light beam produced by a laser diverges much less than the light beam produced by an ordinary light bulb.
4th feature: The laser light can be focused on a very small region.Thanks to its other properties, laser light can be focused in a much smaller region than ordinary light, which makes it possible to obtain extremely high luminous intensities.
Currently, the laser has several applications such as medicine, aesthetic treatments, party animations, among others.